Acoustical treatment



Jan. 9, 1934- M. c. ROSENBLATT ACOUSTICAL TREATMENT Filed March 10, 1928 IN VEN TOR. Ma a/wasdfioszzva; in,"

PF MAM A TTORNEY.

Patented Jan. 9, 1934 ACOUSTICAL TREATMENT Maurice C. Rosenblatt, Philadelphia, Pa. Application March 10, 1928. Serial No. 260,614

Claims.

This invention relates to acoustical treatments.

In a Joint application with Stanley H. Rosenblatt filed November 30, 1926, Serial #151,769, 5 we disclosed an acoustic treatment comprised of pre-formed acoustical units, in which a felt, or other acoustic material, having a contact membrane, was mounted on a reinforcing backing strip, which had numerous advantages over the prior art and practice. In an application filed June 23, 1927, Serial #201,021, I disclosed an acoustic treatment, an essential of which was the formation of a multiplicity of minute pores in the exposed surface of an acoustic material or 16 treatment. Among the materials possessed of sufficient absorption to be classed as acoustic, there are a number of artificial fibre boards, in large measure formed of fibrous material that was formerly waste, but now utilized as fibre or 20 composition boards. Such boards, made by the paper mill and other processes comprise a product the major portion of the fibres of which lie fiatwise in the board. That is, the greater part of the fibres lie in planes parallel with the top and bottom surfaces of the board, and, as an incident in the process of making and finishing the boards, there is a closely compacted layer of fibres at the surfaces of theboards. With the fibres lying in a closely compacted layer in the plane of the surfaces at the exposed surfaces, it

will be evident that the surfaces will be relative- 1y hard and ununiform, with but slight porosity. Despite these untoward factors it is possible for such boards to have an appreciable degree of 36 sound absorption, such a degree, perhaps, as to enable their use as an acoustic material in an acoustic treatment for certain purposes. It is found, however that when such boards are painted or decorated, the pores are filled to such ex- 40 tent as to effect a sharp reduction in their absorbing efiiciency. This is accompanied usual- 1y, by the formation of a surface film which is reflective of impinged sounds. The formation of a multiplicity of minute pores in this film, and in the paste layer which may be used to attach a leveling layer or a membrane over the acoustic material if such are used, has a markedly beneficial effect and increases the absorption, but owing to the nature of the surface of the artificial fibre boards, being relatively hard, and uneven, and h terogeneous, it is resistant to the formation of the pores, requiring greater force and skill in forming the pores, thus increasing the difficulties and cost of the treatment, and possibly resulting in a surface having the artificial pores at some points and not at others, according to the characteristics of the particular fibre board used.

Among the objects of the present invention are; to improve the absorbing efllciency of acoustic materials; to provide an acoustic material of high efiiciency; to render materials available for acoustic treatments that were not previously available; to provide an acoustic material effecting an overall finish; toprovide an acoustic 5 treatment effecting an overall finish without the necessity of an added membrane; to increase the unit sound absorption of a given material;

to provide an acoustic material susceptible to painting or decorating without appreciable reduction of the unit sound absorption; to provide a highly eflicient acoustic treatment at a low cost, both from the square foot cost and the sound absorption cost; to provide an acoustic treatment in which the ends and edges of the fibres with more interstices between the fibres, form the surface exposed to sound waves, with a relatively high absorptive efficiency, in contradistinction to past practices in which a matted fiat mass of fibres with practically no ends 30 of the fibres, and with a minimum of interstices between fibres was the structure of the exposed surface, with relatively low absorptive efiiciency; to provide an acoustic material that is easily worked and applied; to provide an acoustic ma- 35, terial susceptible to use with a backing strip to form pre-formed acoustic units of economy of manufacture and use; to provide an acoustic material susceptible to abrading to effect a. uniform surface without apparent joints; to provide an acoustic material such as will facilitate the formation of a multiplicity of minute pores in its exposed surface in accordance with the application mentioned; and many other objects and advantages as will become more apparent as the description proceeds. I

In the accompanying drawing:

Fig. 1 represents a perspective of a plurality of glued laminations of conventional fibre board from which segments are cut as indicated in dotted lines, which segments are to be turned so that the side edges thereof are exposed,

Fig. 2 represents a section of a wall or ceiling with the acoustic material of the invention in place thereupon to absorb portions of sound waves 5 incident thereon.

Fig. 3 represents a similar section with the acoustic material mounted on a backing strip forming with the material a pre-formed acoustic unit, 1 10 Fig. 4 represents a plan of an attached segment or portion of the acoustic material of the invention, indicating in full linesthe joints between laminations prior to abrading or otherwise treating the surface to conceal the joints,

Fig. 5 represents the same after the assembled treatment has been subjected to the scarifying or abrading action of a sander or other means to secure an overall finish, and

Fig. 6 represents a perspective on an enlarged scale of a fragment of conventional composition fibre board as used in this invention.

The conventional composition board which is available for use in connection with this invention, such as 10, is formed of fibrous materials, almost all of the fibres of which are disposed in planes parallel with the faces of the board, which when calendered or rolled to form the compressed board as available to the public, has upper and lower compacted relatively hard and relatively poreless surfaces 11 and 12 respectively. As previously noted despite this compactness and relative absence of pores such materials have in the past been put to some use in connection with acoustic treatments. The desired acoustic effect has been sought by increasing the area covered by the boards, although if the absorbing efficiency were higher, a smaller area of treatment would sufflce to provide sufficient absorption for the purpose, obviously at a smaller cost. This invention contemplates such savings by increasing the effective absorption of a given composition board. as 10.

Each board 10 has side or edge surfaces 13, which have not heretofore been available nor used for acoustic purposes. It is pointed out, however, that each edge normally formed on the board, and as formed by cutting the board longitudinally and transversely of the upper surface 11, is quite porous, and is highly absorptive of im pinged sound waves. Each side edge being perpendicular to the plane of the upper and lower surfaces, is, in effect, cross-grained, so that the major elements of the surface are the ends and edges of fibres, separated by voids and interstices, making a relatively soft, non-reflective absorbent surface. It is pointed out that the pores and voids are plentifully distributed and are of appreciable depth, such that when such a surface is decorated, as by being painted, the paint is sucked into the pores without forming a skin or film, and because of the depth to which the paint tic purposes comprised of the ends and edges of fibres in large measure, having more pores and I voids than an equal area of a normal composition acoustic material. A material initially and normally possessed of such surfaces as the main surfaces of the composition is within contemplation and is to be considered as within the scope of the invention, although it is preferred to utilize present, and such future embodiments as may be available, commercial products and adapt them to increased usefulness in the acoustic field.

The disclosure herein is purely illustrative as it will be appreciated that it is but necessary that the transverse surfaces of a commercial fibre board be so disposed as to form a sound absorbing surface for acoustical purposes, but the means fastened by mechanical fasteners, etc.

disclosed has proven quick, economical and highly effective.

For general purposes a plurality of fibrous composition boards are glued together, with the upper and lower surfaces 11 and 12 of adjacent boards in contact, to form a block from which segments or sections may be sawed or cut as desired. The block 14 thus formed, has the side edges 13 of the several laminations in substantial registry, so that when sawed or out along a line, as 15, a strip 16 is provided which may be turned so that the exposed surface when mounted in a treatment, will comprise the surfaces 13, transverse to the plane of the laminations.

Each strip 16, which may be cut from a single layer of composition board instead of a plurality of them if desired, when turned for application to a surface to be treated, may be applied to a surface 1''! directly, in any desired manner, as by being glued or pasted to the surface, or by being In some cases it may be found desirable to mount a number of strips 16 on a backing strip 18, and fasten the assembly in place as pre-formed units.

It is preferred to treat the entire surface with the acoustic strips 16, breaking joints preferably by staggering the ends. As a step in the possible complete process according to one phase of the invention, the disclosure of Fig. 4 indicates that the juncture between adjacent laminations, formed by contact of upper surface 11 with lower surface 12 of adjacent layers, may be evident to the eye, under certain conditions. It will be clear that if desired the treatment at this point may be completed by the addition of a membrane and such leveling layers of felt, etc. as may be desired. It is preferred, however, to treat the assembly surface with a scarifier or abrasive in response to which the junctures and meeting lines may be. obliterated. It is pointed out that this is true of the assembly of this invention as the fibres exposed on the surfaces blend and merge with each other to form a unified surface. It is not true of the normal laying of the fibre boards as practiced prior to this invention, inasmuch as the fibres, lying fiat, tear out, and there is no mergence or blending. A motor driven sander or sand blast is preferred for the purpose.

The treatment is one that can be applied by carpenters, with their high skill, as opposed to the conventional use of felt workers as with other forms of acoustic treatments. It is of importance to note that the surfaces so formed may be recoated and redecorated, practically at will, without appreciable detraction from its sound absorption, owing to the depth of its porosity, and if the coating is accompanied by the artificial formation of a multiplicity of minute ports in the surface, the diminution in absorption is trivial.

It will be apparent that with the appreciably higher efficiency from an 'acoustic standpoint available by exposing a surface transverse of the normal fiat face of a given composition material, many materials heretofore unavailable may have such enhanced and increased sound absorption by the invention herein as to render such materials usable in acoustic treatments.

I claim as my invention:

1. A process of acoustically treating surfaces 145 which consists in forming laminations of composition fiber boards, with their flat surfaces in contact, connecting adjacent laminations together, cutting strips from the block thus formed, turning the strips sidewise so that the edge surfaces of the laminations are exposed, and disposing the strips on a surface.

2. An acoustic treatment composed of abutting strips of fibrous composition material with their side or edge surfaces exposed, composed principally of substantially perpendicular fibres, the exposed surface of the treatment being scarified to obliterate the junction between strips by uniting the substantially perpendicular fibres adjacent the junction.

3. The process of acoustically treating a surface consisting in applying abutting strips of fibrous composition material to a surface, with the edge surfaces of the strips exposed and composed principally of substantially perpendicular fibres, then treating the assembled surface with a sanding machine to obliterate the Junction lines in the surface by uniting the substantially perpendicular fibres adjacent the junction.

4. An acoustic treatment having an overall finish without the use of a membrane, comprised of strips of fibrous composition material having exposed surfaces, the material having fibres lying in planes transverse to the exposed surfaces, and the exposed surfaces scarified to cause the obliteration of jointure lines between adjacent strips.

5. An acoustic material comprising a plurality of strips of fibrous composition material having an exposed surface, most of the fibres of the strips of material lying substantially in planes transverse of said surface and laterally interlocked at the junction of strips to conceal the otherwise apparent line of jointure therebetween.

MAURICE C. ROSENBLATT. 

